New vat dyes



United States Patent 1 Claim.

This invention relates to an intermediate for vat dyestuffs having thefollowing formula:

The above compound is useful for the preparation of vat dyestuffs havinglow infrared reflectance. The parent ring will be referred to morebriefly in the specification as Bz-2'-phenyl benzanthrone anthraquinoneacridine.

Dyestuffs for the dyeing of military uniforms present a serious problem.The enormous increase in fire power in modern warfare makes itimperative for soldiers to blend into the terrain so that they areeither unobserved or present relatively poor targets. T he art ofcamouflage resulted in the developmentof uniforms having colors whichblend into the average landscape. During the Second World War,observation by means of infrared radiation completely changed theproblem of camouflage because, while dyes of excellent fastness and dulldrab shades under visible light were generally used for the dyeing ofuniforms, all of the fast dyes with otherwise desirable propertiesshowed high infrared reflectance in the infrared and therefore soldierswearing uniforms dyed with these dyes when observed under infraredradiation, for example by means of devices such as snooperscopes andsniperscopes, stood out against average terrain making discovery easyand presenting excellent targets.

Extensive investigations have shown that to be effective under infraredobservation, dyed fabrics must show an infrared reflectance which isrelatively low, preferably below 25%, but which of course should not betoo low. In other words in average terrain, a soldier to be effectivelyconcealed or to present a poor target should appear no lighter than thebackground and while it is undesirable that a soldier should appear muchdarker, any difference in infrared reflectance from that of the terrainshould be on the darker rather than on the lighter side.

There are known some dyes, for example some sulfur dyes, which exhibitlow infrared reflectance. These dyes, however, have such inferiorfastness to light and to the rather drastic washing conditions in thefield that they 3,030,369 Patented Apr. 17, 1962 are not practical. Onthe other hand, vat dyes which show satisfactory light and wash fastnesshave, in the past, also shown high infrared reflectance. The need forvat dyes of low infrared reflectance and satisfactory fastnessproperties has therefore been unfulfilled, both for use as the only dyesfor uniforms and for use in blends with small amounts of other dyes ofhigher infrared reflectance.

The dyestuffs of the present invention have low infrared reflectance andare sufficiently fast to light, washing, et cetera, to afford acceptablepermanence under military field conditions. The visible shade is suchthat they can be easily blended to the proper shade for uniforms andother military use and their infrared reflectance is so low that theycan be used with dyes of higher infrared reflectance to produce blendshaving satisfactorily low infrared reflectance.

The compounds are prepared by acylating a 4-amino-Bz-2-phenylbenzanthrone anthraquinone acridine, which is in turn a newchemical compound and is included within the scope of the presentinvention. The acylating agents which are suitable for use in preparingthe compound of the present invention include the acid chlorides oranhydrides of benzoic acid, o-toluic acid, p-toluic acid,o-methoxybenzoic acid, p-methoxybenzoic acid, pethoxybenzoic acid,o-butoxybenzoic acid, rn-methylsulfonylbenzoic acid,p-butylsulfonylbenzoic acid, o-chlorobenzoic acid, 2,4-dichlorobenzoicacid, and o-bromobenzoic acid.

The invention will be described in greater detail in conjunction withthe following specific examples, in which the parts are by weight unlessotherwise specified.

Example 1 A mixture of 40 parts of Bz-l-bromo-Bz-Z-phenylbenzanthrone(M.P. 250-252 C. and prepared by bromination of Bz-2-phenylbenzanthronein nitrobenzene), 46 parts of 1-amino-4-benzoylaminoanthraquinone, 10parts of cupric acetate, 61 parts of sodium acetate, and 2,100 parts ofnitrobenzene is stirred at reflux until the reaction is substantiallycomplete. 900 parts of solvent are then distilled out and the mixture iscooled to C., diluted with 600 parts of alcohol, and then cooled to roomtemperature. The violet brown crystalline product is isolated byfiltering, washing with alcohol, boiling in dilute hydrochloric acidslurry, followed by refiltering and washing. It gives a red brown colorin sulfuric acid solution.

Example 2 37 parts of the product of Example 1 are added to a mixture of178 parts of methanol and 333 parts of caustic potash, held at 150 C.The mi: are is stirred at 150 C. until the reaction is substantiallycomplete. It is then drowned in 4,000 parts of ice water, and theresultant slurry is aerated until the product has precipitated. Thelatter is isolated by filtration and washed neutral. It dissolves insulfuric acid with a green coloration.

Example 3 A mixture of 28.5 parts of the product of Example 2, parts ofbenzoylchloride, 2 parts of pyridine, and 60 parts of nitrobenzene isstirred at 145150 C. until the reaction is substantially complete. It iscooled and diluted with 120 parts of alcohol. by filtration and Washedwith alcohol. It is purified by boiling in 50 parts of pyridine,reisolated by filtration and washed with hot pyridine and alcohol. Thedye dissolves in sulfuric acid with an olive green coloration and dyescellulose fibers an olive shade of good fastness and low infraredreflectance.

Example 4 18 parts of the product of Example 2, 3 parts of pyridine, 300parts of nitrobenzene, and 31 parts of 2,4-

The product is isolated dichlorobenzoyl chloride are heated together at-15 0 C. until the reaction is substantially complete. The product isthen isolated as described in Example 3. The product dyes cotton oliveshades of good fastness properties and low infrared reflectance.

Example 5 The procedure of Example 4 is followed using 36 parts ofmeta-methylsulfonylbenzoyl chloride in place of the dichlorobenzoylchloride. A brownish cast solid is obtained which dissolves to a greencolor in sulfuric acid. It dyes textile materials an olive shade of goodfastness properties and low infrared reflectance.

SOgCHs Example 6 No references cited.

